Tail wheel shimmy

[Scott c]

50 hours on my CC and some tail wheel shimmy has started. Any ideas? All landings are three point pavement landings near stall.

[raisedbywolves]

Is the tail wheel and spring tight? Set the tail up on a stand, leaving the spring and wheel hanging, and make sure it's tight. Also what's the angle of the spring look like?

[Dan L]

50 hours on my CC and some tail wheel shimmy has started. Any ideas? All landings are three point pavement landings near stall.

The spring may have lost its arch, especially if you're 3-pointing it on a hard surface. The joint between the tail wheel head and the lower half that rotates should have a positive angle. If that joint appears to be lower in the front than back it will shimmy.

I replaced my my spring with the much more robust Pawnee spring.

[txcub]

50 hours on my CC and some tail wheel shimmy has started. Any ideas? All landings are three point pavement landings near stall.

I just replaced the original 3 leaf spring with the heavier duty PA-18 2 leaf kit from CubCrafters and so far it has helped stopped what little shimmy I had been getting.
Jon

See the previous discussion in this section.
Alaskan Bushwheel Tail Spring • 2 leaf setup • Recommended for 3200 & 3200B tailwheel

[Scott c]

I should have mentioned it has a baby bushwheel and sc spring. I will check angle and the tightness of the bolt. Does greasing improve shimmy at all?

[cityrancher]

Tail spring angle is important. Greasing and check the torque on the retaining nut and bolt may help. They can wear in and loosen a bit.

[Clay Hammond]

Grease and tightness will have zero impact if the angles are off. Check the spring first. And with it sitting on the ground, and under simulated load (when you, your gear, and any passengers are in it the tail weight increases), check the angle of the swivel plane of the tailwheel. You want it to be "leading", not "following". If it is following..a la negative, then you will get the shimmy every time, and more grease and tightening things up won't help.

[cityrancher]

Grease and tightness will have zero impact if the angles are off. Check the spring first. And with it sitting on the ground, and under simulated load (when you, your gear, and any passengers are in it the tail weight increases), check the angle of the swivel plane of the tailwheel. You want it to be "leading", not "following". If it is following..a la negative, then you will get the shimmy every time, and more grease and tightening things up won't help.

As I said, tail spring angle is important. If it is correct, check the torque on the bolt and grease it while you are at it.

[Scott c]

Sure enough nut was bottomed out on the threads. Added a washer and snugged up. Thanks for the help. Will test fly tomorrow.

[Scott c]

Has positive angle.